add Kotlin solution for problem neetcode-gh#271

kotlin/0271-encode-and-decode-strings.kt

@@ -0,0 +1,43 @@
+package kotlin
+
+class Codec {
+ // Encodes a list of strings to a single string.
+ fun encode(strs: List<String>): String {
+ val stringBuilder = StringBuilder()
+ for (string in strs) {
+ for (char in string) {
+ stringBuilder.append(char.toInt()) // char.code in newer version's of Kotlin
+ stringBuilder.append(CHAR_DELIMITER)
+ }
+ stringBuilder.append(STRING_DELIMITER)
+ }
+ return stringBuilder.toString()
+ }
+
+ // Decodes a single string to a list of strings.
+ fun decode(s: String): List<String> {
+ val stringBuilder = StringBuilder()
+ val resultantList = mutableListOf<String>()
+ var i = 0
+ while (i in s.indices) {
+ while (s[i] != STRING_DELIMITER) {
+ var charIntegerValue = ""
+ while (s[i] != CHAR_DELIMITER) {
+ charIntegerValue += s[i]
+ i++
+ }
+ stringBuilder.append(charIntegerValue.toInt().toChar())
+ i++
+ }
+ resultantList.add(stringBuilder.toString())
+ stringBuilder.clear()
+ i++
+ }
+ return resultantList
+ }
+
+ companion object {
+ private const val CHAR_DELIMITER = '|'
+ private const val STRING_DELIMITER = '/'
+ }
+}